The white rot fungus Phanerchaete chrysosporium is able to degrade a wide variety of structurally diverse organopollutants to carbon dioxide. Included among the compounds degraded by this fungus are DDt, polychlorianted biphenyls, dioxins and polyaromatic hydrocarbons. A major objective of the overall project proposal is to develop an effective and economical system which uses P. chrysosporium to treat hazardous organochemical wastes. It has been shown that the ability to degrade organopollutants is due to the non-specific and non-stereoselective lignin degrading system of this fungus that is induced by nutrient (nitrogen, carbohydrate or sulfur) starvation. Furthermore, it has been shown that the lignin depolymerizing enzymes (also known as ligninases or lignin peroxidases) which are secreted under these conditions, are able to catalyze the initial oxidation of many organopollutants. Therefore, in order to understand the enzymology of biodegradation in this fungus and to understand why this microorganism is able to degrade such a wide array of compounds, a detailed knowledge of these enzymes and their relative abilities to oxidize difficult-to-degrade organopollutants is needed. Thus the specific aims of this project are to: 1) purify and characterize ligninase isozymes secreted by P. chrysosporium, 2) Determine the relative ability of ligninases and two comparable mammalian peroxidases (lactoperoxidase and PGH synthase) to oxidize polyaromatic hydrocarbons, 3) Determine the relative ability of ligninases and two comparable mammalian peroxidases to oxidize selected "difficult-to-degrade" organohalides, 4) To determine if certain peroxidase substrates are able to function as "co-oxidants" and promote the oxidation of compounds that are not substrates for ligninases, 5) To determine if hydroperoxides other than hydrogen peroxides may serve as the oxidizing co-substrate for ligninases and 6) To characterize and compare ligninases produced by recombinant DNA technology with ligninases isolated from P. chrysosporium.